Conventionally, an image forming apparatus of an electrophotographic type such as an electrophotographic copying machine uses a developer (toner) of fine particles. In such an image forming apparatus, the developer (toner) is supplied from the developer supply container in response to consumption thereof resulting from image forming operation.
As for a conventional developer supply container, a type in which the toner is supplied using the air is known.
For example, Japanese Laid-open Patent Application Hei 10-268641 and Japanese Laid-open Patent Application 2000-199994 employ an air feeding type in which a screw pump and an air pump are provided between a toner accommodation case and a developing device, and the toner is fed by pressure upwardly toward the developing device from the toner accommodation case by such pumps.
In addition, Japanese Laid-open Patent Application Hei 10-268641 and Japanese Laid-open Patent Application 2000-199994 use a filter (venting member), provided before the developing device, for separating the toner and the gasses from each other, because if the mixture of the toner and the air is supplied into the developing device, the toner blows out of the developing device with the result of the deterioration of the image quality.
However, with the devices disclosed in Japanese Laid-open Patent Application Hei 10-268641 and Japanese Laid-open Patent Application 2000-199994, the problems which will be described below may arise because of the employment of the air feeding type for feeding the toner by pressure.
Here, the filter has to permit the air discharging but prevents passage of the toner, and for this reason, it is unavoidable that the filter is clogged.
Thus, in the case of the structure disclosed in Japanese Laid-open Patent Application Hei 10-268641 and Japanese Laid-open Patent Application 2000-199994 using the air feeding type in which the toner is fed by pressure, the air pressure is applied to the filter in one way, that is, in the air discharging direction only, with the result that the filter becomes clogged with the toner in a short term. As a result, the discharging function of the filter is deteriorated, and the toner may blows out of the developing device, which leads to the deterioration of the image quality.
Accordingly, it is an object of the present invention to provide a developer supply container and a developer supplying system in which the clogging of the venting member with the developer can be suppressed.
It is another object of the present invention to provide a developer supply container and an image forming apparatus in which the deterioration of the image quality attributable to the clogging of the venting member with the developer can be suppressed.
These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the embodiments of the present invention, taken in conjunction with the accompanying drawings.